Organic Light-Emitting Diode (OLED) display devices possess merits such as self-illumination, fast response, high contrast, wide viewing angle, and the like, and have become one type of display device receiving extensive attention currently.
An OLED display device comprises a plurality of pixels arranged in a matrix, each of the pixels is controlled and driven to display gray scales by a pixel driving circuit of this pixel. For conventional pixel driving circuits, image display function of the OLED display device is realized by driving corresponding OLEDs in the pixels with driving switching transistors. During the work process of a driving switching transistor, the gate electrode of the driving switching transistor can be in a state with a high bias voltage for a long time, and the physical characteristics of the driving switching transistor can become unstable under the high bias voltage for the long time, a threshold voltage drifting phenomenon for the driving switching transistor can be easily caused, and a normal output corresponding to a scan signal can be adversely affected.